1. Field of the Invention
The present invention relates to an apparatus and a method for irradiating a scattering medium.
2. Description of the Related Art
Vellekoop et al. demonstrated that focusing light through scattering medium is possible by controlling the incident wavefront with spatial light modulator (SLM) and their phase optimization algorithm (Vellekoop, I. et al, Opt. Lett. 32(16), 2309-2311 (2007)). They infer an optimal incident wavefront in such a way that the target intensity monitored by a CCD becomes highest at given segment (pixel) on the SLM by cycling its phase from 0 to 2π. Once they finished optimizing the wavefront, the incident light which has the optimized wavefront can focus light at a CCD plane.
Focusing light just after passing through a scattering medium is possible by controlling the wavefront of the incident light with the SLM. The position of the focus point obtained by this technique, however, is not inside the scattering medium but behind the medium where light is transmitted.
Vellekoop et al. further disclosed the way to focus light inside the scattering medium where a fluorescence probe lies (Vellekoop, I. et al, Opt. Express 16, 67-80 (2008)). The focused light intensity can be monitored by a CCD and control a SLM to optimize the incident wavefront for focusing. However, positions of fluorescence probes in a sample cannot be controlled.